Children, 12 to 24 months of age, were presented with three tasks: two detour problems and a spatial task. The aim of the study was to assess the performance on each task and to consider the relationship between performance on the two detour problems and the relationship between spatial knowledge and detour ability. The two detour tasks (the lever task and the bent wire task) shared a common feature in that the object rather than the subject had to be moved in the detour. The results of the lever task indicated that age, experimental group (three lever designs were used) and the sex of subjects were influential variables. Analysis of the bent-wire data showed that as hypothesised age was the most important variable, accounting for qualitative and quantitative differences in performance. The results from the detour tasks were discussed with reference to the attainment of skilled behaviour and the relationship between cognitive development and detour ability. Spatial task results indicated that performance was related to age and that the type of error recorded was also related to the age of the subject. The hypothesised relationship between the two detour tasks was not supported by the data. Furthermore, the anticipated relationship between detour ability and spatial knowledge failed to emerge. These results were discussed in relation to the issue of developmental synchrony and the structuralist's view of development.